Subject: [PATCH] arm64: dts: Fix GIC reg sizes for APM X-Gene

From: [email-masked] (Marc Zyngier)
Date: Wed, 11 Mar 2015 17:31:15 +0000

On 11/03/15 17:19, Feng Kan wrote:
> On Wed, Mar 11, 2015 at 7:53 AM, Marc Zyngier <[email-masked]> wrote:
>> On 27/01/15 07:03, Pranavkumar Sawargaonkar wrote:
>>> In APM X-Gene, GIC register space is 64K aligned while the sizes mentioned
>>> in the dt are 4K aligned. This breaks KVM when kernel is built with 64K page
>>> size due to size alignment checking in vgic driver for VCPU Control and
>>> VCPU register.
>>>
>>> This patch corrects the sizes to be inline with the hardware spec.
>>
>> This patch may be correct, but it is useless. The firmware on my APM
>> system (some version of u-boot) repaints the DT at boot time, negating
>> the effect of this patch.
> We have updated u-boot to reflect this change. I can supply you with a updated
> image if you wish.

That would be useful, thanks.

But more importantly, why bother upstreaming your DT into the kernel
tree if your firmware is going to overwrite whatever we provide?

Either the firmware let the user provide its own DT (and doesn't touch
it other than to change the CPU enable method, insert a /memreserve/ or
similar things), or the firmware always provide its own DT, and doesn't
let the user provide its own. Corrupting the user DT is a disaster, as
we just found.

Thanks,

	M.

>>
>> Another system I can remove from my 64k-capable list.
>>
>>         M.
>>
>>> CC: linux-arm-kernel at lists.infradead.org
>>> CC: kvmarm at lists.cs.columbia.edu
>>> CC: arnd at arndb.de
>>> CC: marc.zyngier at arm.com
>>> CC: christoffer.dall at linaro.org
>>> CC: jcm at redhat.com
>>> Signed-off-by: Pranavkumar Sawargaonkar <[email-masked]>
>>> Signed-off-by: Tushar Jagad <[email-masked]>
>>> Signed-off-by: Feng Kan <[email-masked]>
>>> ---
>>>  arch/arm64/boot/dts/apm/apm-storm.dtsi |    8 ++++----
>>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/apm/apm-storm.dtsi b/arch/arm64/boot/dts/apm/apm-storm.dtsi
>>> index f1ad9c2..65f0e6d 100644
>>> --- a/arch/arm64/boot/dts/apm/apm-storm.dtsi
>>> +++ b/arch/arm64/boot/dts/apm/apm-storm.dtsi
>>> @@ -81,10 +81,10 @@
>>>               compatible = "arm,cortex-a15-gic";
>>>               #interrupt-cells = <3>;
>>>               interrupt-controller;
>>> -             reg = <0x0 0x78010000 0x0 0x1000>,      /* GIC Dist */
>>> -                   <0x0 0x78020000 0x0 0x1000>,      /* GIC CPU */
>>> -                   <0x0 0x78040000 0x0 0x2000>,      /* GIC VCPU Control */
>>> -                   <0x0 0x78060000 0x0 0x2000>;      /* GIC VCPU */
>>> +             reg = <0x0 0x78010000 0x0 0x10000>,     /* GIC Dist */
>>> +                   <0x0 0x78020000 0x0 0x20000>,     /* GIC CPU */
>>> +                   <0x0 0x78040000 0x0 0x10000>,     /* GIC VCPU Control */
>>> +                   <0x0 0x78060000 0x0 0x20000>;     /* GIC VCPU */
>>>               interrupts = <1 9 0xf04>;       /* GIC Maintenence IRQ */
>>>       };
>>>
>>> --
>>> 1.7.9.5
>>>
>>>
>>
>>
>> --
>> Jazz is not dead. It just smells funny...
> 

-- 
Jazz is not dead. It just smells funny...